About 25,000 of world's top AIDS researchers, political leaders, diplomats and other stakeholders are gathering for Sunday's International AIDS Conference.

The biennial conference will take place July 22-27 in Washington, a city faced with one of the United States' highest rates of HIV infections. The HIV virus usually leads to AIDS.

Secretary of State Hillary Clinton, former President Bill Clinton and former first lady Laura Bush will speak at the conference. Other high-level speakers include World Bank President Jim Yong Kim, and Microsoft chairman and philanthropist Bill Gates.

AIDS is a disease that alters the immune system, making people much more vulnerable to infections and diseases.

HIV is found in the body fluids of an infected person and is passed from one person to another through blood-to-blood contact, sexual contact, or from a mother to her child during pregnancy or through breast feeding.

The United Nations says 34 million people lived with HIV/AIDS and 1.7 million died from the disease in 2011.

On Friday, U.N. Secretary-General Ban Ki-moon appointed Michel Kazatchkine as his special envoy for HIV/AIDS in Eastern Europe and Central Asia, where HIV continues to grow.

Last week Mr. Ban appointed former U.N. Deputy Secretary-General Asha-Rose Migiro as the special envoy for HIV/AIDS in Africa, the continent most affected by HIV.